Tow/ Haul on FORD 22000 lb chassis

[starburst2]

I read my Ford manual but did not understand what the Tow/Haul switch is suppose to do. Although I have owned the rig for 5 months I only had 5 days of ownership before it was pranged my some drunk and it has been in the repair shop since Aug 6th. Thus I know virtually nothing about the coach and we are getting anxious to head out in it by the end of the week. What does the tow/haul do. I thought it was like a retarder of some kind to help you slow down on grades kindsa like the exhaust brake on my previous diesel pusher. When decending on the downhill slope of the Rocky Mountains I put it in Tow/Haul but it did not hold me back much, it just reved the engine up to high RPMs forcing me to apply brakes to reduce the engine RPM's. Is it more for actually pulling up the grade? Is it similar to a dowwnshift? Is it a torque converter lookup? What does it do or supposed to help in doing?
Lloyd

[jsutherl]

You'll want to find and download the Ford F53 Chassis manual for your rig. I can't find the link right now.

Here's what the manual for my 2007 Chassis says about Tow Haul:

Tow/Haul delays upshifts to reduce frequency of transmission shifting.
Tow/Haul also provides engine braking in all forward gears when the
transmission is in the D (Overdrive) position; this engine braking will
slow the vehicle and assist the driver in controlling the vehicle when
descending a grade. Depending on driving conditions and load
conditions, the transmission may downshift, slow the vehicle and control
the vehicle speed when descending a hill, without the accelerator pedal
being pressed. The amount of downshift braking provided will vary based
upon the amount the brake pedal is depressed.

Grade braking downshifts occur automatically when:
• positive vehicle acceleration (natural acceleration from driving on a
decline) is sensed.
• nearly all pressure is released from the accelerator pedal.
• a minimum amount of time has expired since the last grade braking
downshift.

Grade braking downshift mode is immediately exited if the Tow/Haul
mode is deactivated or if the accelerator pedal is depressed beyond a
minimum threshold.
To deactivate the Tow/Haul feature and return to normal driving mode,
press the button on the end of the gearshift lever. The TOW HAUL light
will no longer be illuminated.
When you shut-off and restart the engine, the transmission will
automatically return to normal D (Overdrive) mode (Tow/Haul OFF).

[starburst2]

Thanks
Thats pretty much as I understood the function of tow/haul. Somehow it did not match my experiences. Perhaps I have been spoiled by the exhaust brake on the diesel and expected something similar after reading the dissertation in the manual.
Again, thank you for your feedback .
Lloyd

[starburst2]

I should have added that before the diesel I had a Southwind on the P-30 chassis with the 7.3 litre Chevy V8, When descending the Siskiyou Summit in southern Oregon, in the Soutwind, the engine compression held me back quite good, much better than the Tow/haul does. I'm headed south in the next few days so I'll get to experience the engine braking characteristics again soon.
Lloyd

[jsutherl]

I hope that it works for you. I haven't had opportunity to tackle any long down grades yet.

Lots of interesting things in that manual. Such as the engines ability to run at reduced power with no coolant.

[starburst2]

I never read about that. Thanks for your feedback jsutherl. I hope I get a better braking experience on this trip. I also hope I never have to find out how it runs without coolant. Thats a scary prospect. I don't know how your engine could stand up to that sort of punishment and not destroy itself.
Regards,
Lloyd

[jsutherl]

Apparently it shuts off half the cylinders and those serve as air pumps to cool the engine. It also says the it'll shut down the engine before it gets to a temperature that would hurt it.

I hope I never have to find out either!

[jsutherl]

Here's what the manual says:

What you should know about fail-safe cooling
If the engine coolant supply is depleted, this feature allows the vehicle to be driven temporarily before incremental component damage is incurred. The “fail-safe” distance depends on ambient temperatures, vehicle load and terrain.
How fail-safe cooling works
If the engine begins to overheat:
• The engine coolant temperature gauge will move to the red (hot) area.
• CHECK GAUGES will illuminate in the mini message center
• The Service engine soon indicator light will illuminate.
If the engine reaches a preset over-temperature condition, the engine will automatically switch to alternating cylinder operation. Each disabled cylinder acts as an air pump and cools the engine.
When this occurs the vehicle will still operate. However:
• The engine power will be limited.
• The air conditioning system will be disabled.
Continued operation will increase the engine temperature and the engine will completely shut down, causing steering and braking effort to increase.

Once the engine temperature cools, the engine can be re-started. Take your vehicle to an authorized dealer as soon as possible to minimize engine damage.

[nemo45]

Try driving with the cruise control on while you are in tow haul. I'm sure you'll notice a huge amout of downshifting and engine breaking, so much so that I hardly ever use tow haul. I just put 2000 miles on my rig driving down to south Texas the round about way and loved the way the V10 performed. Got 7.5 to 8 mpg towing my motorcycle on a trailer. But, I only drove 60 mph on the interstates as we were with other campers.

[whitebb]

TOW HAUL
The way I remember tow haul works it locks out the over drive and I still have 5 speeds. I went 7000 miles out north west and had several 6-7 8 % grades and when I reached top say 50 mph look at % signage and if needed press brake once to change to 4 gear and precede down hill and if needed press brake lightly to keep slower speed I needed or press a litter harder to change to 3 gear. Sure engine makes louder sound until you reach smaller incline. I never toe with over drive on. Transmission shifts up and down and is hard on tyranny. This works for me. The F53 and 5 speed did a great job.
I hope this helps.

[johnnypal]

My last coach had a workhorse chassis and let me tell you this ford tow haul aint no workhorse w22 with tranny brake.With the workhorse I was able to desend steep grades out west without ever touching the brake.With the ford tow haul the coach tends to run away even on moderate grades.Workhorse is no longer building RV chassis because of their big recall on defective calipers but I am sure going to miss them.

[nemo45]

Originally Posted by johnnypal

My last coach had a workhorse chassis and let me tell you this ford tow haul aint no workhorse w22 with tranny brake.With the workhorse I was able to desend steep grades out west without ever touching the brake.With the ford tow haul the coach tends to run away even on moderate grades.Workhorse is no longer building RV chassis because of their big recall on defective calipers but I am sure going to miss them.

The 2011 Ford V10 Chassis has a transmission brake also. If I did this right you can read about it in the attachment.

Motorhome_ClassA_Catalog.pdf

[starburst2]

Well I am now in Palm springs area and the motorhome performed admirably. The breaking on hills was pretty darn good. I can't say it was as good as an exhaust brake but it was good.
I was even more surprised by the hill climbing ability. Although not recommended for good gas mileage I put it in cruise at 55 mph and I went over the Siskiyou summit and only dropped down 5 mph. The engine was torquing it pretty good and the tach showed it was reved up to 4000 RPM but it went over the summit passing even the diesels except for those without any trialer in tow. I was impressed.
Lloyd

[BOBFIDY]

.....4000 RPM.......I'll bet that thing sounded like a chain saw.
Not sure I want to buzz mine that high RPM for very long.
Just saying.......

[nemo45]

4000 rpm doesn't sound too bad. But, if you have the cruise set at about 62 mph and you go up a grade like that it, pops up to about 4800 rpm and that is pretty nerve racking.